music theory for musicians and normal people by toby w. rush
Species Counterpoint: Species IV with the fourth species, we stop using smaller note values and back up a bit to species I. But instead of having the notes move at the same time, species IV involves the voices being offset from one another.
&C Ó ˙ ˙ ˙ ˙ ˙ ˙ ˙ ˙ ˙ ˙ ˙ ˙ ˙ 5 3 6 7 6 7 6 3 6 7 6 4 3 w w w w w w ?C w
The biggest difference with species IV is the fact that dissonances are permitted on the downbeat. but as you might expect, they have to follow certain specific rules.
dissonances in species IV must be in the form of suspensions. A suspension is a dissonant note that is approached by being held over — suspended — from the previous note.
&C ˙ ˙ ˙ ˙
another important defining characteristic is that the suspension resolves down by step. if it doesn’t resolve down by step, it’s not a suspension!
?C w 6
we label suspensions by the intervals of the suspension and resolution, so this one would be called a 7-6 suspension.
&C ˙ ˙
˙ ˙ w
similarly, in this example, 8 6 4 3 the suspended note is the D, which forms a fourth with the A. it moves to a C, a third above the bass, making it a 4-3 suspension.
the 7-6 and 4-3 suspensions are the only ones fux allows when writing counterpoint above the cantus firmus.
oh you don’t say.
in this case, the suspension is the F on the downbeat of the second measure. it’s prepared by the F in the previous measure, and resolves down to the E. suspensions are great, by the way, but don’t use the same one more than three times in a row, or fux will release the hounds.
the only suspension fux allows when writing counterpoint below the cantus firmus is the 2-3 suspension, in which the suspended note forms a second with the cantus firmus, then resolves down to a third. (when this suspension is written an octave lower, it is sometimes called a 9-10 suspension.)
w 5 3 2 3 ˙ ˙ ˙ ?C ˙
see how we resolve to a larger interval, unlike the 7-6 or 4-3? we’re below the cantus firmus, so we move away from it. because suspensions always resolve down!
in species IV, you’re dealing with a lot of limitations with melody and counterpoint, so you will sometimes get trapped in a situation where nothing will work. when this happens, you are allowed to “break species”: forget the tie and slip into species II for a couple of notes. aker! species bre for example, here we break species so we 8 4 3 can avoid writing a 4 3 4 3 6 5 6 8 6 fux-enraging four 4-3 suspensions in a row!
&C Ó ˙ ?C w
˙ ˙ w
˙ ˙ w
˙ ˙ w
˙ ˙ w
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don’t go crazy with this, though... species IV counterpoint should embrace suspensions, not avoid them. it’s best to break species only rarely. unfortunately, sometimes that means backing way up and choosing a different starting pitch for your counterpoint! licensed under a creative commons BY-NC-ND license - visit tobyrush.com for more
A discussion of the rules of fourth species counterpoint.